Anti-Factor Xa chromogenic assays, in tandem with rivaroxaban calibrators and controls, provide the most accurate quantitative measurement of rivaroxaban plasma concentrations.
How should rivaroxaban exposure be assessed in the laboratory when necessary?
When assessment of rivaroxaban exposure is needed, anti-Factor Xa chromogenic assays can measure drug concentration, though clinicians must interpret results alongside pharmacokinetics and patient bleeding risk factors.
Research into new anticoagulants for preventing and treating thromboembolic disorders has focused on targeting single enzymes in the coagulation cascade, particularly Factor Xa and thrombin, inhibition of which greatly decreases thrombin generation. Based on the results of phase III clinical trials, rivaroxaban, a direct Factor Xa inhibitor, has been approved in many countries for the management of several thromboembolic disorders. Owing to its predictable pharmacokinetic and pharmacodynamic characteristics, fixed-dose regimens are used without the need for routine coagulation monitoring. In situations where assessment of rivaroxaban exposure may be helpful, anti-Factor Xa chromogenic assays (in tandem with standard calibration curves generated with the use of rivaroxaban calibrators and controls) could be used. It is important to note that test results will be affected by the timing of blood sampling after rivaroxaban intake. In addition, the anti-Factor Xa method measures the drug concentration and not the intensity of the drug's anticoagulant activity, and a higher than expected rivaroxaban plasma level does not necessarily indicate an increased risk of bleeding complications. Therefore, clinicians need to consider test results in relation to the pharmacokinetics of rivaroxaban and other patient risk factors associated with bleeding.
Samama et al. (Tue,) conducted a review in Thromboembolic disorders. Rivaroxaban was evaluated. Anti-Factor Xa chromogenic assays, in tandem with rivaroxaban calibrators and controls, provide the most accurate quantitative measurement of rivaroxaban plasma concentrations.